首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   203篇
  免费   4篇
儿科学   5篇
妇产科学   2篇
基础医学   11篇
口腔科学   5篇
临床医学   14篇
内科学   17篇
皮肤病学   2篇
神经病学   6篇
特种医学   96篇
外科学   28篇
综合类   5篇
预防医学   3篇
眼科学   1篇
药学   6篇
肿瘤学   6篇
  2022年   1篇
  2021年   2篇
  2019年   1篇
  2018年   2篇
  2015年   3篇
  2014年   4篇
  2013年   4篇
  2012年   2篇
  2010年   5篇
  2009年   2篇
  2008年   2篇
  2007年   4篇
  2006年   7篇
  2005年   1篇
  2004年   8篇
  2003年   9篇
  2002年   4篇
  2001年   6篇
  2000年   1篇
  1999年   2篇
  1998年   7篇
  1997年   9篇
  1996年   10篇
  1995年   6篇
  1994年   11篇
  1993年   6篇
  1992年   1篇
  1991年   3篇
  1990年   4篇
  1989年   6篇
  1988年   9篇
  1987年   6篇
  1986年   9篇
  1985年   8篇
  1984年   3篇
  1983年   5篇
  1982年   7篇
  1981年   4篇
  1980年   12篇
  1979年   1篇
  1978年   3篇
  1977年   1篇
  1976年   3篇
  1975年   2篇
  1973年   1篇
排序方式: 共有207条查询结果,搜索用时 15 毫秒
31.
Patients with dilated stenoses and recanalized occlusions were evaluated to assess the initial and long-term results of percutaneous transluminal angioplasty (PTA) in the femoropopliteal artery. The follow-up period was at least 1 year. The initial success rate was 84% (128/164). The initial results were influenced by the radiologist's experience, catheter selection, and type of lesion. The 5- and 7-year cumulative patency rates were 70% and 60%. There was no difference in long-term patency between initially successful stenoses and short (less than 3 cm) occlusions. Both the morphology and location of the stenotic lesion influenced the long-term results. Although many factors influence the initial and long-term success rate, results of this study justify PTA in the femoropopliteal artery. Patients with localized stenoses and short occlusions are best suited for this treatment.  相似文献   
32.
Ho  PS; Yu  SW; Sether  LA; Wagner  M; Ho  KC; Haughton  VM 《Radiology》1988,169(1):87-91
Magnetic resonance (MR) imaging, correlated with anatomic sections, was used to characterize the progressive and regressive changes in the nucleus pulposus in neonates. The spines of five fetuses and five full-term infants between 16 and 40 weeks old were studied. In anatomic sections, the nucleus pulposus was sharply demarcated from the anulus fibrosus, Sharpey fibers were conspicuous, and a plate of primitive notochord was evident in the equator of the disk. On long repetition time (TR)/long echo time (TE) or long TR/short TE MR images, Sharpey fibers (low signal intensity) and notochord (low signal intensity) could be differentiated from the high-signal-intensity nucleus pulposus and anulus fibrosus. The major differences between the fetal and infant spines were the amount of notochord in the disk and ossification in the vertebral body.  相似文献   
33.
34.
35.

INTRODUCTION

The aim of this study was to investigate whether incidence rates of tonsil and base of tongue cancer in England are increasing using data from the UK cancer registry.

SUBJECTS AND METHODS

Cancer registrations for oral cavity and oropharynx cancer from 1985–2006 in England were obtained from the National Cancer Information Service. Population estimates were obtained from the Office for National Statistics. Age-adjusted incidence rates and age-specific incidence rates were calculated. The sexes were considered separately as incidence rates are known to differ significantly between men and women. Linear regression was performed to establish whether there was a relationship between incidence rates and time.

RESULTS

There has been an increase in all oral cavity and oropharyngeal cancer in the study period. Linear regression analysis suggests that approximately 90% of the variance in age-adjusted incidence rates for men and women for tonsil, base of tongue and other oral cavity cancer is explained by the passage of time. For other oropharyngeal cancer, the variance is 62% and 46% in men and women, respectively. The estimated annual percentage change from 1985 to 2006 in age-adjusted incidence rates for tonsil and base of tongue cancer is 5.7% and 6.7% for men, and 4.3% and 6.5% for women, respectively.

CONCLUSIONS

This study confirms a wide-spread clinical impression that there has been an increase in age-adjusted incidence rates, between 1985 and 2006, in all oral cavity cancer in England. The age range 40–69 years has seen the biggest increases in age-specific incidence rates for tonsil and base of tongue cancer. This reflects the findings of similar studies in other countries.  相似文献   
36.
37.
38.
39.

Introduction

The purpose of this study was to develop a convolutional neural network (CNN) to determine the extent of over-scanning in the Z-direction associated with lung computed tomography (CT) examinations.

Materials and methods

The CT examinations of 250 patients were used to train the machine learning software and 100 were used to validate the results. Each lung CT examination was divided into cervical, lung, and abdominal areas by the CNN and 2 independent radiologists, and the length of each area was measured. Every part above or below the lung marks was labeled as over-scanning. The accuracy of the CNN was calculated after the training phase and agreement between CNN and radiologists was assessed using kappa statistics during the validation phase. After validation the software was used to estimate the length of each of the three areas and the total over-scanning in further 1000 patients.

Results

An accuracy of 0.99 was found for the testing dataset and a very good agreement (kappa = 0.98) between the CNN and the radiologists’ evaluation was found for the validation dataset. Over-scanning was 22.8% with the CNN and 22.2% with the radiologists. The degree of over-scanning was 22.6% in 1000 lung CT examinations.

Conclusion

Our study shows a substantial over estimation of the length of the area to be scanned during lung CT and thus an unnecessary patient's over-exposure to ionizing radiation. This over-scanning can be assessed easily, reliably and quickly using CNN.  相似文献   
40.
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号